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Abstract
Anterior cruciate ligament (ACL) injury is one of the most common injuries in sport and brings with it life changing consequences. A considerable financial burden ($17,000) may be accompanied by strength deficiencies, mood disturbances and chronic pain. While long term outcomes may include secondary injury, osteoarthritis and a decreased quality of life. Although these debilitating injuries are frequently associated with contact sports, the majority (70-80%) occur in a non-contact manner and, thus, may be preventable. ACL injury risk reduction programs have been shown to be effective in the short term; however, they lack retention. Hence, it is essential to continue to enhance existing risk reduction strategies. It is highly recommended to include ACL injury risk reduction programs as part of an individual's training prior to engaging in sport. These programs typically target specific biomechanics that have been identified as high risk factors for ACL injuries. While they have shown short-term effectiveness in improving these risk factors, the challenge lies in sustaining these changes throughout the athletic season, which can compromise their injury reduction effectiveness. Traditionally injury risk reduction programs have relied on feedback directed towards the body’s movement (internal focus of attention), while research has shown that feedback directed towards the outcome of the movement (external focus of attention) is more effective for learning and performance of movement as well as retention of learned movements. However, the most effective mode of external focus of attention feedback has yet to be established. Therefore, our aims were to: 1. Evaluate the effectiveness of internal focus of attention feedback vs. external focus of attention feedback at improving high risk biomechanics associated with a non-contact ACL injury and retaining those improvements; 2. Compare the effectiveness of two novel modes of external focus of attention feedback (visual and auditory) at improving high risk biomechanics associated with a non-contact ACL injury. We did not find any significant differences in biomechanics between groups following the internal focus of attention and external focus of attention feedback or between the two modes of external focus of attention (visual and auditory). Thus, our findings do not support prior studies that demonstrate the effectiveness of different modes of feedback in modifying injury risk biomechanics. We did, however, identify statistically significant limb asymmetries regardless of feedback or time point. We also observed post intervention changes in Landing Error Scoring System scores and patient reported outcomes regardless of feedback. It is possible that applying different modes of feedback during different exercises or in individuals with pre-existing "at risk" biomechanics at baseline may return different results. The study also highlights the potential need to screen for limb asymmetries and individualizing the program to address any discrepancies.